Materials with good stretchability and elasticity are used to manufacture a variety of disposable articles in addition to durable articles including incontinence pads, disposable diapers, training pants, clothing, undergarments, sports apparel, automotive trim, weather-stripping, gaskets, and furniture upholstery. For clothing, stretchability and elasticity are performance attributes that allow the materials to provide a closely conforming fit to the body of the wearer.
While numerous materials are known to exhibit excellent stress-strain properties and elasticity at room temperatures, it is often desirable for elastic materials to provide a conforming or secure fit during repeated use, during extensions and retractions at elevated or depressed temperatures, or in automobile interiors during summer months. Elasticity at elevated temperatures is also important for maintaining tight tolerances throughout temperature cycles. In particular, elastic materials used for repeated wear clothing or garments must maintain their integrity and elastic performance after laundering.
Spandex™, a segmented polyurethane urea elastic material, is currently used in various durable fabrics. For example, fibers made from Spandex™ have been used in launderable apparels, fabrics, durable and disposable furnishing, beddings, etc. Similar to conventional uncrosslinked polyolefin-based elastic materials, articles made from Spandex™ can lose integrity, shape, and elastic properties when subjected to elevated temperatures. Thus, Spandex™ may not be suitable for many co-knitting applications with high temperature fibers, such as polyester fibers.
Accordingly, there is still a need for new and improved propylene-based materials and articles therefrom, such as fibers and films, of elastic polyolefins that have good thermal resistance, stretchability, and elasticity.